About

I'm hoping to import road surface data provided by the Vermont State government in order to assist in adding full coverage of road surface data for the state. As far as I'm aware, I'm the only OSM contributor who has added road surface tags in Vermont and I would like to use data from the State government to assist my efforts.

This import would add surface=* tags to existing OSM ways that are tagged as highway=*. No additional geometry will be added.

Import Plan Outline

Goals

Import road-surface data for the state of Vermont, USA.

Existing ways tagged as highway=* will have surface=* tags added/updated.

Impassible/Untraveled ways will be tagged as highway=track,surface=dirt

Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: SURFACE
Attribute_Value_Accuracy_Explanation:
Roads surface types are generally based on VTrans Town Highway
Maps, or on regional/local review. Little or no photo
interpretation was done, but road shapes and distances
were originally used to assign SURFACE codes. Some regional
and local knowledge has been used to update SURFACE
codes in updated datasets (see the updates listing).
Legal trails and discontinued roads were all originally
assigned SURFACE equals 9 (unknown).
The surface types of some very short roads could not be
determined from the VTrans maps, especially differentiating
between gravel (2) and soil (3). Surface types for these
arcs were coded 'unknown' (9), or a best judgement was
made. The Town Highway Maps are being generated from the TransRoad_RDS
data and require public highways to have surface code other than
9. The QA/QC process flags highways that don't comform and are
corrected.

Way/Shape Matching

OSM ways are matched first by name to records in the TransRoad_RDS shapefile. The bounding box of the way is then compared to the bounding box of the record in the shapefile by adding the absolute value of the difference of each bbox side. If the difference in bounding box extent is greater than 10km the record is ignored as a potential match. Potential matches are then ordered by closest bounding box match. The best match is used as the primary value and matches that are up to twice the extent of the closest match are considered.

Example:

The OSM way 12345 has a name of "Elm St" and a bounding box (S,W,N,E) of 44.0000,-73.0001,44.0001,-73.0000.

The best-fit shape has a bounding box difference of 125 meters, so only shapes with differences up to 250 meters will be considered. There are two shapes that fall into this match; since they both have the same surface (#1 - Hard surface) we will consider that the surface for this way. If there was a shape with a difference under 250 meters that had a different surface we would consider this a mixed result and not apply a tag to the way.

Tag mapping

1 - Hard surface (paved) adds surface=paved if the surface is not already one of surface=asphalt, surface=asphalt, surface=concrete.